Cycloidal Cycloidal gearbox gearboxes or reducers consist of four simple components: a high-speed input shaft, a single or compound cycloidal cam, cam followers or rollers, and a slow-speed output shaft. The insight shaft attaches to an eccentric drive member that induces eccentric rotation of the cycloidal cam. In compound reducers, the first an eye on the cycloidal cam lobes engages cam followers in the housing. Cylindrical cam followers become teeth on the inner gear, and the number of cam fans exceeds the amount of cam lobes. The next track of substance cam lobes engages with cam followers on the output shaft and transforms the cam’s eccentric rotation into concentric rotation of the output shaft, thus increasing torque and reducing acceleration.
Compound cycloidal gearboxes offer ratios ranging from as low as 10:1 to 300:1 without stacking stages, as in regular planetary gearboxes. The gearbox’s compound reduction and can be calculated using:
where nhsg = the number of followers or rollers in the fixed housing and nops = the number for followers or rollers in the slower rate output shaft (flange).
There are many commercial variations of cycloidal reducers. And unlike planetary gearboxes where variations are based on gear geometry, heat therapy, and finishing procedures, cycloidal variations share fundamental design principles but generate cycloidal movement in different ways.
Planetary gearboxes are made up of three fundamental force-transmitting elements: a sun gear, three or even more satellite or world gears, and an internal ring gear. In an average gearbox, the sun gear attaches to the input shaft, which is linked to the servomotor. Sunlight gear transmits electric motor rotation to the satellites which, subsequently, rotate in the stationary ring gear. The ring equipment is section of the gearbox casing. Satellite gears rotate on rigid shafts connected to the earth carrier and cause the earth carrier to rotate and, thus, turn the output shaft. The gearbox provides result shaft higher torque and lower rpm.
Planetary gearboxes generally have one or two-equipment stages for reduction ratios which range from 3:1 to 100:1. A third stage can be added for actually higher ratios, nonetheless it is not common.
The ratio of a planetary gearbox is calculated using the next formula:where nring = the amount of teeth in the inner ring gear and nsun = the number of teeth in the pinion (input) gear.
Comparing the two
When deciding between cycloidal and planetary gearboxes, engineers should initial consider the precision needed in the application form. If backlash and positioning precision are necessary, then cycloidal gearboxes offer the best choice. Removing backlash can also help the servomotor manage high-cycle, high-frequency moves.
Following, consider the ratio. Engineers can do that by optimizing the reflected load/gearbox inertia and acceleration for the servomotor. In ratios from 3:1 to 100:1, planetary gearboxes provide best torque density, weight, and precision. In fact, few cycloidal reducers offer ratios below 30:1. In ratios from 11:1 to 100:1, planetary or cycloidal reducers can be used. However, if the mandatory ratio goes beyond 100:1, cycloidal gearboxes keep advantages because stacking phases is unnecessary, so the gearbox could be shorter and less expensive.
Finally, consider size. Most manufacturers offer square-framed planetary gearboxes that mate exactly with servomotors. But planetary gearboxes grow in length from one to two and three-stage styles as needed gear ratios go from significantly less than 10:1 to between 11:1 and 100:1, and to higher than 100:1, respectively.
Conversely, cycloidal reducers are bigger in diameter for the same torque but are not as long. The compound decrease cycloidal gear train handles all ratios within the same bundle size, therefore higher-ratio cycloidal gear boxes become also shorter than planetary versions with the same ratios.
Backlash, ratio, and size provide engineers with an initial gearbox selection. But selecting the most appropriate gearbox also requires bearing capability, torsional stiffness, shock loads, environmental conditions, duty cycle, and life.
From a mechanical perspective, gearboxes have grown to be somewhat of accessories to servomotors. For gearboxes to execute properly and provide engineers with a stability of performance, life, and value, sizing and selection should be determined from the load side back again to the motor instead of the motor out.
Both cycloidal and planetary reducers are appropriate in any industry that uses servos or stepper motors. And although both are epicyclical reducers, the distinctions between the majority of planetary gearboxes stem more from equipment geometry and manufacturing processes instead of principles of operation. But cycloidal reducers are more varied and share small in common with each other. There are advantages in each and engineers should think about the strengths and weaknesses when choosing one over the various other.
Great things about planetary gearboxes
• High torque density
• Load distribution and posting between planet gears
• Smooth operation
• High efficiency
• Low input inertia
• Low backlash
• Low cost
Great things about cycloidal gearboxes
• Zero or very-low backlash remains relatively constant during existence of the application
• Rolling instead of sliding contact
• Low wear
• Shock-load capacity
• Torsional stiffness
• Flat, pancake design
• Ratios exceeding 200:1 in a concise size
• Quiet operation
The need for gearboxes
There are three basic reasons to employ a gearbox:
Inertia matching. The most typical reason for choosing the gearbox is to regulate inertia in highly dynamic circumstances. Servomotors can only control up to 10 times their own inertia. But if response period is critical, the electric motor should control less than four situations its own inertia.
Speed reduction, Servomotors operate more efficiently at higher speeds. Gearboxes help keep motors working at their optimum speeds.
Torque magnification. Gearboxes offer mechanical advantage by not only decreasing quickness but also increasing output torque.
The EP 3000 and our related products that use cycloidal gearing technology deliver the most robust solution in the most compact footprint. The primary power train is made up of an eccentric roller bearing that drives a wheel around a couple of inner pins, keeping the decrease high and the rotational inertia low. The wheel incorporates a curved tooth profile rather than the more traditional involute tooth profile, which gets rid of shear forces at any stage of contact. This design introduces compression forces, instead of those shear forces that could can be found with an involute gear mesh. That provides numerous overall performance benefits such as for example high shock load capability (>500% of rating), minimal friction and put on, lower mechanical service factors, among numerous others. The cycloidal style also has a huge output shaft bearing span, which gives exceptional overhung load features without requiring any additional expensive components.
Cycloidal advantages over various other styles of gearing;
Able to handle larger “shock” loads (>500%) of rating compared to worm, helical, etc.
High reduction ratios and torque density in a concise dimensional footprint
Exceptional “built-in” overhung load carrying capability
High efficiency (>95%) per reduction stage
Minimal reflected inertia to motor for longer service life
Just ridiculously rugged as all get-out
The overall EP design proves to be extremely durable, and it requires minimal maintenance following installation. The EP may be the most reliable reducer in the commercial marketplace, in fact it is a perfect suit for applications in large industry such as oil & gas, primary and secondary steel processing, industrial food production, metal slicing and forming machinery, wastewater treatment, extrusion devices, among others.